1. Field of the Invention
The present invention relates to a relay apparatus which relays a signal between an image forming device and a post-processing device which have different interfaces, and an image forming system including the relay apparatus.
2. Description of Related Art
To a subsequent stage of an image forming device which prints out an image by forming the image on a sheet, one or a plurality of post-processing devices having each function to perform processing such as punching, stitching, and folding, and to bundle a plurality of sheets to create a brochure are connected in series. Thereby, an image forming system is configured.
In such an image forming system, various types of information are exchanged between the image forming device and the post-processing device in order to match various sheet conditions (sheet size, paper type, and basis weight) or post-processing conditions. For example, the information is exchanged in the following sequences.
At the timing of feeding a sheet from a sheet feeding unit of the image forming device, the image forming device notifies the post-processing device of the sheet feed information including the sheet information relating to the above sheet and the post-processing information indicating the contents of post-processing to be performed for the above sheet. Based on the notified sheet feed information, each post-processing device calculates time necessary for the post-processing in the post-processing device and time corresponding to a sheet interval, and notifies the image forming device of the above calculated time. The image forming device allows the fed sheet to stand by at a predetermined standby position provided on the way to a carrier path, and releases a standby state to discharge the sheet at the timing corresponding to the time notified by the post-processing device. By this control, a sheet interval necessary for the post-processing device is secured.
For the purpose of performing post-processing for creating brochures, the set separation information indicating the separation between two sets of document is further needed in addition to the above-described sheet feed information. It is required to notify the set separation information of the post-processing device between the sets of document (an interval from a final sheet of the set to a first sheet of the next set). Therefore, in the above-described sequence, the set separation information is notified to the post-processing device in synchronization with the sheet feed information of the final sheet.
FIG. 20 shows a connection example in the case where an image forming device and a plurality of post-processing devices are connected in series through serial interfaces (I/F) of the same communication system (protocol). In such a connection state, the information is sent in order from upstream to downstream (image forming device→post-processing device 1→post-processing device 2→post-processing device 3) or from downstream to upstream, and the information is transmitted.
FIG. 21 shows a specific example in the case where sheet feed information is notified through the above-described sequence in an image forming system shown in FIG. 20. In this example, there is shown a communication sequence in which a punch process is performed in the post-processing device 1, a sheet is carried by a bypass conveyance in the post-processing device 2 (a sheet is carried to a subsequent-stage post-processing device without performing post-processing), and a side stitching process is performed in the post-processing device 3 to create two sets of brochures each of which has two sheets.
Every when one sheet is fed, the image forming device outputs sheet feed information (sheet information and post-processing information) relating to a sheet to be fed and carried to the subsequent-stage post-processing devices. The sheet feed information is transmitted in order from the image forming device to the post-processing device 1→the post-processing device 2→the post-processing device 3. In FIG. 21, a suffix added to each piece of information indicates that the sheet number of the sheet corresponding to the information and the set number of the set including the above sheet. To be more specific, “1-1”, “1-2”, “2-1”, and “2-2” indicate a first sheet of a first set, a second sheet of the first set, a first sheet of a second set, and a second sheet of the second set, respectively.
Based on the received sheet feed information, each post-processing device calculates time of a sheet interval necessary for post-processing (time for allowing a sheet to stand by in the image forming device). Then, each post-processing device notifies wait information indicating the calculated time in the order of the post-processing device 3→the post-processing device 2→the post-processing device 1→the image forming device to notify the image forming device of the wait information. The wait information is sent back for each piece of sheet feed information (for each sheet). For example, the wait information 2-1 indicates a sheet interval between the second sheet of the first set and the first sheet of the second set.
By stopping a sheet temporarily at a standby position in accordance with the time indicated by the wait information notified from the post-processing device, the image forming device secures the time (sheet interval) necessary for the post-processing device. For example, the standby time at the standby position in the image forming device (timing for releasing the standby state) is controlled so as to set the time until the first sheet of the second set is discharged (output timing of the sheet discharge information 2-1) after the second sheet of the first set is discharged (output timing of the sheet discharge information 1-2), to the time indicated by the wait information 2-1.
Further, in synchronization with the sheet feed information, the set separation information is transmitted in order, specifically, from the image forming device to the post-processing device l→the post-processing device 2→the post-processing device 3 after the sheet feed information relating to the final sheet of each set. That is, the set separation information is notified significantly before the final sheet of the set is actually discharged to the post-processing device. In addition, the sheet discharge information is notified to a subsequent-stage device in accordance with the timing at which a sheet is discharged from each device.
In recent years, a post-processing device in the image forming system has been diversified into various kinds. The demand that not only a post-processing device of a manufacturer which manufactures an image forming device but also a post-processing device of a different manufacturer (hereinafter, referred to as a third vendor) is connected and operated on line, has been increased.
On the other hand, with regard to the connection of the post-processing device in the image forming system, each communication specification for exchanging information is not standardized and unified.
In this background, it is inefficient that each third vendor is compliant with complicated interface specifications of a manufacturer which manufactures the image forming device. To solve the above problem, a parallel interface is adopted as a simple interface which is common to each third vendor. It is not necessary for a third vendor to be conscious of the interface specification of a manufacturer of the image forming device main body and the interface specification of each manufacturer, and a post-processing device can be developed and provided by using only a simple interface. Note that in the case of parallel communication, the set separation information needs to be notified in synchronization with the sheet discharge information.
Further, as shown in FIG. 22, the following image forming device is proposed (see Japanese Patent Application Publication No. 2006-350961). In the image forming device, both a serial interface and a parallel interface are provided, and a post-processing device (genuine device) which is compliant with the serial interface and a post-processing device (third vendor device) which is compliant with the parallel interface can be connected.
In addition, the technique for notifying a subsequent-stage post-processing device of the sheet information at the timing at which each post-processing device discharges a sheet therefrom or at the timing at which a sheet is carried to a predetermined position, is disclosed (see Japanese Patent Application Publication Nos. 2007-079539 and 2007-106594). The technique for connecting an inserter device via a post-processing device, is disclosed (see Japanese Patent Application Publication No. 2008-191593). The technique for providing an interface device which connects a plurality of post-processing devices to an image forming device and managing a plurality of post-processing devices, for example, by determining the post-processing device to be used, in accordance with the contents of post-processing, is disclosed (see Japanese Patent Application Publication No. 2003-155160).
In the parallel interface, the amount of information to be exchanged is very small as compared to the serial interface. Therefore, for example, it is necessary to limit the function of controlling the device (third vendor device) connected through the parallel interface as compared to a conventional system. Further, the necessary information is stored in another unit, for example, the storage unit of the image forming device.
In case that a post-processing device (genuine device) which is compliant with a serial interface a manufacturer of an image forming device and a post-processing device (third vendor device) which is compliant with a parallel interface are mixed to configure an image forming system, because a number of combinations of types of devices to be connected and the number of the devices to be connected are considered, it is difficult for the image forming device to have interfaces for all post-processing devices and to handle all connection patterns.
In the set separation information, the image forming device which is a genuine device and which performs the above-described communication sequence of FIG. 21, outputs the set separation information in synchronization with the sheet feed information. The third-vendor post-processing device which performs communication through the parallel interface is required to receive the set separation information in synchronization with the sheet discharge information. Accordingly, some sort of control is required in order to connect the post-processing device which is a third vendor device and which performs communication through the parallel interface, to the image forming device which is the genuine device and which performs the communication sequence of FIG. 21.
For example, in case that the post-processing device which is the genuine device and the post-processing device which is the third vendor device compliant with the parallel interface, are mixedly connected to the image forming device, when the image forming device controls the transmission timing of the set separation information, the image forming device allows any of the post-processing device which is the third vendor device and the post-processing device which is the genuine device to perform the post-processing for creating a brochure. In addition, based on various post-processing conditions, it is required to change the control for transmitting the set separation information. Therefore, it is required to add the function for changing the above control to the image forming device main body. Further, when the number of types of the third vendor device to be connected is increased, it is very troublesome that the necessary functions are added to the image forming device so as to handle all the third vendor devices.
Further, because the heights at which the carrier inlet and the carrier outlet for the sheets are disposed from the installation surface are also different from each other depending on the third vendor devices, it is required to adjust the above heights in order to connect the third vendor device to the image forming system and carry the sheet.
The techniques disclosed in the above Japanese Patent Application Publications, do not solve the problem which is caused when the set separation information output from the image forming device is notified to a post-processing device having a different communication system.